"Catalyzes the synthesis of carbamoyl phosphate from ATP, ammonium and bicarbonate. Proceeds via a three-step mechanism, i.e. the phosphorylation of hydrogencarbonate to carboxyphosphate, a nucleophilic attack of ammonia on carboxyphosphate yielding carbamate, and the phosphorylation of carbamate forming carbamoyl phosphate."xsd:string